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Two products with the same goal, two different shapes. Here's where each one wins, where it doesn't, and how to pick.

Monica is the elder statesman of the personal-CRM space - mature, open-source, and self-hostable. Contact Book is younger and lighter, with a sharper UI, live multi-tab updates, and a deliberately small surface. If you want to self-host on a Pi and tinker, Monica is hard to beat. If you want a clean, fast personal CRM that you don't run yourself, with bilingual support and a hosted plan that costs less than two coffees a month, that's us.
Both products want to give you a single calm place to keep the people in your life. Monica gets there with a comprehensive feature surface accumulated over years of community contribution. Contact Book gets there with a sharper, more opinionated subset and a fast UI on top.
The honest take: if you tested both and only had ten minutes per app, you'd probably feel us as faster and Monica as more configurable. Pick whichever feeling matters more.
Monica's hosted plan runs in France under EU law. Ours runs in Germany under German law. For most users this is academic - the EU GDPR baseline is the same. If you have a corporate or legal requirement specifically pointing at Germany, that's a clear win for us. If you don't, treat the two as equivalent on this axis and pick on UX.
Free plan, no credit card. We host in Germany. You can export and delete everything self-serve.

Written by
Co-Founder + CEO
Julia is one of the Co-Founders. She handles design, product direction, and most of the support replies that arrive in the morning.
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| Ours Contact Book | Theirs Monica | |
|---|---|---|
Self-hostable | ||
Open source | ||
Hosted plan available | ||
Hosted in Germany (EU) | France (EU) | |
Live multi-tab updates (websocket) | ||
Bilingual UI (EN + DE) | Multiple, EN+DE included | |
Stay-in-touch cadence | ||
Gifts tracker | ||
Activity / journal log | ||
Pets | ||
API + drop-in clients (15 langs) | API only | |
MCP server for AI agents | ||
Hosted price (per month) | From €1 | $9 / €9 |